Morphology and phylogenetic analysis of five deep-sea golden gorgonians (Cnidaria, Octocorallia, Chrysogorgiidae) in the Western Pacific Ocean, with the description of a new species

Yu Xu; Zifeng Zhan; Kuidong Xu

doi:10.3897/zookeys.989.53104

Morphology and phylogenetic analysis of five deep-sea golden gorgonians (Cnidaria, Octocorallia, Chrysogorgiidae) in the Western Pacific Ocean, with the description of a new species

Zookeys. 2020 Nov 9:989:1-37. doi: 10.3897/zookeys.989.53104. eCollection 2020.

Authors

Yu Xu^{1

2}, Zifeng Zhan^{1

3}, Kuidong Xu^{1

3

4

2}

Affiliations

¹ Laboratory of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China Institute of Oceanology, Chinese Academy of Sciences Qingdao China.
² University of Chinese Academy of Sciences, Beijing 100049, China Center for Ocean Mega-Science, Chinese Academy of Sciences Qingdao China.
³ Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China University of Chinese Academy of Sciences Beijing China.
⁴ Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China Pilot National Laboratory for Marine Science and Technology Qingdao China.

Abstract

Explorations of seamounts in the Western Pacific Ocean and South China Sea resulted in collecting 18 specimens of golden gorgonians. Based on the morphology and the genetic analysis of mtMutS, they are described as one new species, Chrysogorgia carolinensis sp. nov., and four known species, including Chrysogorgia dendritica Xu, Zhan & Xu, 2020, Metallogorgia melanotrichos (Wright & Studer, 1889), Metallogorgia macrospina Kükenthal, 1919, and Pseudochrysogorgia bellona Pante & France, 2010. Chrysogorgia carolinensis belongs to the Chrysogorgia "group A, Spiculosae" with rods or spindles distributed in the polyp-body wall and tentacles, and differs from all of its congeners except C. dendritica by the 1/3L branching sequence and amoeba-shaped sclerites at the basal polyp body. The mtMutS sequence of C. carolinensis sp. nov. has six deletion mutations compared to those of its congeners, supporting the establishment of the new species. Although no genetic variability was observed between the closely related species C. dendritica and C. abludo Pante & Watling, 2012, the former is different from the latter by the apparently irregular sclerites in the polyp body wall. The two specimens of Metallogorgia melanotrichos match well with the original description except for relatively larger polyps, while the M. macrospina specimens have slightly smaller polyps than the holotype. The juvenile of Metallogorgia has an obvious morphological difference with the adults in the colony shape and branches, but they can be unified by the same polyps and sclerites as well as mitochondrial MutS sequences. Thus, the generic diagnosis of Metallogorgia is slightly extended to include the morphology of juveniles. The morphology of Pseudochrysogorgia bellona Pante & France, 2010, as a new record for the South China Sea, matches well with that of the original description. In the phylogenetic trees, the Chrysogorgia species are separated into two clades, and while Metallogorgia and Pseudochrysogorgia formed a sister clade.

Keywords: Anthozoa; Metallogorgia; Pseudochrysogorgia; Chrysogorgia carolinensis; Chrysogorgia dendritica; seamount.

Yu Xu, Zifeng Zhan, Kuidong Xu.